Phoenix police were still on the scene after a Wednesday evening attack left a priest shot and killed and another injured at the Roman Catholic church the Mother of Mercy Mission on Thursday, June 12, 2014, in Phoenix. Police have no suspects at this point, but they are canvassing the neighborhood and going over physical evidence from the scene. (AP Photo/Ross D. Franklin)

PHOENIX (AP) – Police said the investigation into a deadly priest shooting at a Roman Catholic church in Phoenix has been stymied by a lack of usable surveillance video and a vague account of the attack by a second severely injured clergyman.

Still, investigators have been able to recover forensic evidence from the dead priest's car and the crime scene that they are hopeful will lead them to a suspect. And they are going door to door in the neighborhood looking for witnesses who might have seen something.

The investigation is playing out as parishioners are mourning the loss of the Rev. Kenneth Walker, 28, and praying for the recovery of the Rev. Joseph Terra, 56, who was so badly beaten in the Wednesday night attack in the rectory of their church that police were worried he wouldn't survive the night. He remained in critical but stable condition.

Police said Terra told them the next day the suspect was a white male in his 40s, but they acknowledge it was a "limited description."

"Unfortunately because of the severity of his injuries, he was only able to provide limited information about one particular suspect," Phoenix police Sgt. Steve Martos said.

In a recording of the 911 call released by police Friday, Terra can be heard breathing heavily and pausing as the dispatcher asked him what happened.

"No, no he's not," Terra said as he is then instructed how to perform CPR.

He was unable at the time to provide a description of who attacked him and fatally shot Walker.

"You have no description at all?" the dispatcher asked.

"No," Terra replied.

Police and paramedics soon arrived on the scene, and Terra "pretty much just shut down then, went into survival mode," Martos said Friday.

He said detectives weren't suspicious that Terra couldn't describe his attacker at the time, but later was able to provide a limited description.

"That's not uncommon. You're talking about an individual who was just severely attacked," Martos said, adding that authorities didn't think he would survive. "Especially with the vicious assault that he had just endured."

Martos said Terra was trying to save Walker's life until authorities arrived, even as he himself lay critically wounded.

"He's doing everything he can because he's the only one there," Martos said.

Detectives have collected surveillance video from buildings in the area, including government facilities near the state Capitol, but they found nothing usable at this point because the cameras weren't pointed at the church.

Police are still unsure if there was only one suspect or whether robbery was the motive in the attack at the Mother of Mercy Mission, Martos said. He declined to said whether there was forced entry.

Investigators have been able to rule out several theories, including speculation of a dispute between the priests.

"There's nothing to indicate that this is priest on priest or Father Terra getting into some argument or discussion with Father Walker," Martos said. "We don't believe that. The evidence that we have come across does not point in that direction at all."

Walker was born in upstate New York, had 10 siblings and was drawn to the priesthood after attending traditional Latin Mass with his family in high school. He later joined the seminary, made good grades and enjoyed playing soccer, said the Rev. Joseph Lee, academic dean at the Our Lady of Guadalupe Seminary in Nebraska.

Walker eventually joined a Catholic order that specializes in Latin Mass and became a priest in downtown Phoenix. He recently officiated a younger sibling's wedding in Kansas — the last time he saw many relatives.

Family members said they were overcome with emotion by the loss, but they took solace in the fact that the surviving priest was able to administer last rites.

"For Catholics, receiving your last rites basically guarantees you're going to heaven," said Walker's stepsister, Sasha Keys. "That's one of the biggest reasons we have to smile."

In his application to the seminary, Walker spoke of his devotion to God and desire to be a priest.

"The only vocation that I could be satisfied with, as a work," he wrote, "would be one that would be ... dedicated to bringing people to salvation in whatever way God wills for me to do so. This work is best carried out by the priesthood."